X-ray marker for artificial femoral heads



Dec. 23, 1952 M. ROSENSTEIN X-RAY MARKER FOR ARTIFICIAL FEMORAL HEADS Filed Jan. 5, 1952 /flllllllfrlllr lll Illlllll INVENTOR MAX ROSENSTEIN BY 7% WZM/ ATTO R N EY atented Dec. 23, 1952 UNITED STATES PATENT OFFICE X-RAY MARKER FOR ARTIFICIAL FEMORAL HEADS 1 Claim.

The present invention relates to artificial femoral heads of transparent material, such as synthetic resins, and more particularly to a position marker in such transparent artificial prostheses.

Artificial transparent femoral heads have been used heretofore in hip arthroplasty but once the femoral heads were in position in the human body, subsequent X-rays failed to reveal whether the head had changed its position, the generally circular and spherical contours of the prosthesis and its parts giving no indication of possible rotational displacement. Since even the slightest dislocations may be of considerable importance, this has been a serious disadvantage.

In accordance with the present invention, there is provided an opaque eccentric marker, preferably of metal, said marker being built into the interior of the transparent femoral head. Allsteel heads are also known, but it would not be possibl to apply such a position marker to the exterior of such a prosthesis since it would create friction between the prosthesis and the bone with which it cooperates. The opaque marker built into the transparent head will appear on an X-ray picture and will signify the exact position of the artificial femoral head at the time of or immediately after the operation. Subsequent X-ray pictures will, by comparison, show whether there has been any dislocation of the prosthesis.

The invention will be more fully described in connection with the single figure of the accompanyin drawing showing an artificial femoral head. In the drawing, l is the substantially hemispherically shaped transparent head and 2 is the stem which secures the head in the bone. As illustrated, the stem is provided with longitudinal grooves 3 which will produce a more solid connection between the bone and the stem. The stem is preferably tapered at the end. The stem and head may be made of any suitable transparent material which remains inert in the human body and various synthetic resins have been found satisfactory. Acrylic and methacrylic polymers have been found suitable but the present invention is not concerned with any specific substance for femoral heads, such substances being known in the art.

Th plastic head and stem are cast on a core of metal, such as steel, comprising a rod 4 corresponding to stem 3 and a disc 5 placed concentrically in head I. Disc 5 carries eccentric stud 6 which fixes the position of the femoral head in the bone. Any rotational movement of the head will result in a movement of position marker 6, easily ascertainable by comparison of X-ray pictures.

The femoral head of the present invention is used in th following manner:

The femoral neck is severed and the femoral head is removed. Thereupon, the neck is perforated from end to end, preferably so that the tunnel-like opening is so oriented that the head is in a slightly coxa-vagoid position. The surface of the neck is then smoothed and so prepared that the base of the artificial head is received in as close a fit as possible. The selected size of prosthesis is then introduced into the fore hole and driven in by means of the drivehead until, by transparency, the rim of the neck is seen to adhere completely to the groove formed by the head at its junction with the stem. After careful reconstruction of the capsule, the muscular and cutaneous planes are closed.

Position marker 5 will appear clearly on any X-ray picture since it is formed of opaque material, preferably integrally with the disc 5.

What is claimed is:

An artificial prosthesis comprising a transparent femoral head and a stem integral therewith, a metal core comprising a disc concentrically arranged in said head and a rod co-axially arranged in said stem, and a metal stud eccentrically secured to said disc.

1VIAX ROSENSTEIN.

REFERENCES CKTED The following references are of record in the file of this patent:

The Journal of Bone a Joint Surgery for May 1950, p. 167.

The Journal of Bone & Joint Surgery for October 1951, advertising p. 39.

(Copies of these publications in the Scientific Library.) 

